1. Field of the Invention
Exemplary embodiments of the present invention relate to a thin-film transistor (TFT) substrate and a method of fabricating the same and, more particularly, to a TFT using an oxide semiconductor and a method of fabricating the TFT.
2. Discussion of the Background
Thin-film transistors (TFTs) are used as switching elements in flat panel displays such as liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays. In a conventional LCD, a channel layer of a TFT is mostly an amorphous silicon layer. In this case, the TFT has a mobility of approximately 0.5 cm2/Vs. However, as displays become larger, high resolution and high-frequency driving capabilities are required. Accordingly, a high-performance TFT with high mobility is in demand and research is being conducted on an oxide semiconductor layer having a higher mobility than the amorphous silicon layer. For example, a Ga—In—Zn—O layer has mobility of several tens of times greater than the mobility of an amorphous silicon layer, thus exhibiting excellent semiconductor characteristics.
Further, the ON current of a TFT is proportional to the mobility of a channel layer and the width of the channel layer and indirectly proportional to the length of the channel layer. Therefore, when an oxide semiconductor having high mobility is used for a TFT, the ON current of the TFT may be increased, depending on the physical attributes and semiconductor composition of the channel region.